Sensors are used for detecting electromagnetic radiation such as heat radiation or infrared radiation. Motion detectors detect, for example, persons, by detecting the heat radiation emitted by the persons. Temperature detectors may be used to determine the temperature of an object, and photo detectors may detect the amount of incident light being directed toward a sensor element.
Surface mount technology (SMT) is used for constructing electronic circuits where the components (surface-mounted components/SMCs) are mounted directly onto the surface of printed circuit boards (PCBs). An electronic device so made is called a surface mount device (SMD). SMT has largely replaced the through-hole technology construction method of fitting components with wire leads into holes in the circuit board.
An SMT component is usually smaller than its through-hole counterpart because it has either smaller leads or no leads at all. It may have short pins or leads of various styles, flat contacts, a matrix of solder balls (BGAs), or terminations on the body of the component.
An SMT sensor package may contain a lid or cover portion bonded to a base, where the circuit components are attached to the base. The cover portion and/or the base may each be so designed to form a cavity region above the base, and the cavity region may be substantially sealed, such that a vacuum or quasi-vacuum is within the cavity, for example, to protect the circuit from contaminants or particles that may interfere with the operation of sensor components. The cavity may similarly be filled with a gas, for example, an inert gas. The cover generally includes a transparent area or window configured to permit transmission of some forms of electromagnetic radiation. The window may perform additional functions, for example, filtering certain wavelengths, or focusing, shaping or diverting electromagnetic radiation using, for example, one or more lenses. The window may also perform a combination of these functions, for example, both filtering and focusing or diverting functions.
An exemplary apparatus and process for iso-thermally sealing electronic packages with a thermosetting adhesive is disclosed by the European Patent Application 91200724.2, entitled “Iso-thermal seal process for electronic devices,” is incorporated by reference herein in its entirety.
Manufacturing costs for SMT sensor packages may be high relative to other electronic components due to complexities in constructing and assembling the components described above. Therefore, there is a need in the industry to manufacture SMT sensor packages at a lower cost.